Kepler's laws

Meanings

1. The three laws of planetary motion discovered by Kepler in the early 17th century, stating that (i) the orbit of a planet is an ellipse with the Sun at one of the two foci, (ii) a line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time, and (iii) the square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.

Etymology

For Johannes Kepler, German mathematician and astronomer.